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San Andreas Mining District, Mother Lode Belt, Calaveras Co., California, USAi
Regional Level Types
San Andreas Mining DistrictMining District
Mother Lode BeltBelt
Calaveras Co.County
CaliforniaState
USACountry

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Key
Latitude & Longitude (WGS84):
38° 11' 45'' North , 120° 40' 45'' West
Latitude & Longitude (decimal):
Locality type:


Location: This district is in west-central Calaveras County. It consists of that part of the Mother Lode gold belt that extends from the North Branch-Cottage Springs area southeast through San Andreas and Kentucky House to the vicinity of Fourth Crossing. It is both a lode- and placer-mining district.

History. The streams were mined during the early part of the gold rush. San Andreas Gulch was first settled by Mexicans in 1848 or 1849. The Tertiary channel deposits were mined by hydraulicking and drifting from the 1850s through the 1880s, and some drift mining has continued until the present time. Lode mining also began in the 1850s. Numerous lode mines were active from the 1870s until about 1900 and again during the 1930s. The Union gold mine was prospected for uranium in the middle 1950s.

Geology: The area is underlain by northwest-trending belts of greenstone, amphibolite schist, slate, and lenticular serpentine bodies. At Kentucky House, a large body of dolomitic limestone contains lenses of high-calcium limestone mined by the Calaveras Cement Company. To the east of San Andreas is a granodiorite stock. Overlying portions of the district are numerous deposits of auriferous Tertiary channel gravels.

Ore Deposits: The lode deposits consist of northwest-trending quartz veins with stringers that contain finely divided free gold and pyrite. The veins occur principally in amphibolite and greenstone. Most of the milling ore averages '/j ounce of gold per ton or less, but several of the ore shoots have been mined to depths of 700 feet. Considerable high-grade ore was taken from shallow workings during the early days. Small amounts of tellurides and uranium minerals have been found in this district.

Mines: Lode: Commodore, Etna, Everlasting, Fellowcraft, Ford, Gottschalk, Golden Hill, Helen, Holland, Kate Hageman, Lookout Mtn., Mester, Pioneer Chief, Rathgeb, Thorpe, Union ($200,000+).

Placer: Benson, Central Hill, Lloyd, North Branch, Rising Star, Wheats.

Regions containing this locality

Pacific OceanOcean
North America PlateTectonic Plate

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Standard Detailed Strunz Dana Chemical Elements

Commodity List

This is a list of exploitable or exploited mineral commodities recorded from this region.


Mineral List

Mineral list contains entries from the region specified including sub-localities

14 valid minerals.

Rock Types Recorded

Note: this is a very new system on mindat.org and data is currently VERY limited. Please bear with us while we work towards adding this information!

Rock list contains entries from the region specified including sub-localities

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Alphabetical List Tree Diagram

Detailed Mineral List:

'Allanite Group'
Formula: {A12+REE3+}{M3+2M32+}(Si2O7)(SiO4)O(OH)
Reference: Knopf, Adolf (1929), The Mother Lode system of California: USGS Professional Paper 157, 88 pp.: 35; Murdoch, Joseph & Robert W. Webb (1966), Minerals of California, Centennial Volume (1866-1966): California Division Mines & Geology Bulletin 189: 60.
Ankerite
Formula: Ca(Fe2+,Mg)(CO3)2
Reference: Tucker, W. Burling (1916), Amador, Calaveras, Tuolumne Counties: California Mining Bureau. Report 14: 82; Murdoch, Joseph & Robert W. Webb (1966), Minerals of California, Centennial Volume (1866-1966): California Division Mines & Geology Bulletin 189: 76.
Antigorite
Formula: Mg3(Si2O5)(OH)4
Description: γ = 1.573, α = 1.562, & birefringence = .010.
Reference: Knopf, Adolf (1929), The Mother Lode system of California: USGS Professional Paper 157, 88 pp.; […(abstract): Engineering & Mining Journal: 128: 24 (1929); […Geol. Zentralbl., Band 41: 364-367 (1930)]: 36; Pemberton, H. Earl (1983), Minerals of California; Van Nostrand Reinholt Press: 421.
Calcite
Formula: CaCO3
Chalcopyrite
Formula: CuFeS2
Reference: U.S. Geological Survey, 2005, Mineral Resources Data System: U.S. Geological Survey, Reston, Virginia.
'Chlorite Group'
Description: A component of chloritic felsite.
Reference: USGS (2005), Mineral Resources Data System (MRDS): U.S. Geological Survey, Reston, Virginia, loc. file ID #10102669.
Dolomite
Formula: CaMg(CO3)2
Reference: U.S. Geological Survey, 2005, Mineral Resources Data System: U.S. Geological Survey, Reston, Virginia.
Gold
Formula: Au
Localities: Reported from at least 80 localities in this region.
Hessite
Formula: Ag2Te
Description: Occurs in the main vein. Carries some gold.
Reference: Knopf, Adolf (1929), The Mother Lode system of California: USGS Professional Paper 157, 88 pp: 39; Clark, Wm. B. & P.A. Lydon (1962), Mines and mineral resources of Calaveras County, California: California Division of Mines & Geology County Report 2: 51; Murdoch, Joseph & Robert W. Webb (1966), Minerals of California, Centennial Volume (1866-1966): California Division Mines & Geology Bulletin 189: 218; Pemberton, H. Earl (1983), Minerals of California; Van Nostrand Reinholt Press: 109.
'Hornblende'
Description: Occurs in the country rock.
Reference: USGS (2005), Mineral Resources Data System (MRDS): U.S. Geological Survey, Reston, Virginia, loc. file ID #10028861.
'Mariposite'
Formula: K(Al,Cr)2(Al,Si)4O10(OH)2
Description: Occurs in schist.
Reference: Knopf, Adolf (1929), The Mother Lode system of California: USGS Professional Paper 157, 88 pp.: 38; Murdoch, Joseph & Robert W. Webb (1966), Minerals of California, Centennial Volume (1866-1966): California Division Mines & Geology Bulletin 189: 256.
Muscovite
Formula: KAl2(AlSi3O10)(OH)2
Description: Occurs in schist.
Reference: Knopf, Adolf (1929), The Mother Lode system of California: USGS Professional Paper 157, 88 pp.: 38; Murdoch, Joseph & Robert W. Webb (1966), Minerals of California, Centennial Volume (1866-1966): California Division Mines & Geology Bulletin 189: 256.
Muscovite var: Phengite
Formula: KAl1.5(Mg,Fe)0.5(Al0.5Si3.5O10)(OH)2
Description: Occurs in schist.
Reference: Knopf, Adolf (1929), The Mother Lode system of California: USGS Professional Paper 157, 88 pp.: 38; Murdoch, Joseph & Robert W. Webb (1966), Minerals of California, Centennial Volume (1866-1966): California Division Mines & Geology Bulletin 189: 256.
Petzite
Formula: Ag3AuTe2
Description: Occurs in the main vein.
Reference: Storms, William H. (1899), Characteristic gold mines of the California gold belt: Mining and Scientific Press: 79: 108; Ransome, Frederick Leslie (1900), Description of the Mother Lode district, California: USGS Geol. Atlas, Mother Lode (No. 63), 11 pp.: 9; Knopf, Adolf (1929), The Mother Lode system of California: USGS Professional Paper 157, 88 pp.: 39; Clark, Wm. B. & P.A. Lydon (1962), Mines and mineral resources of Calaveras County, California: California Division of Mines & Geology County Report 2; [… Geological Society of America Proceedings, 1933: 312-313, 1934]: 51; Murdoch, Joseph & Robert W. Webb (1966), Minerals of California, Centennial Volume (1866-1966): California Division Mines & Geology Bulletin 189: 286; Pemberton, H. Earl (1983), Minerals of California; Van Nostrand Reinholt Press: 109.
'Psilomelane'
Formula: Mn, O
Reference: Bradley, W.W., et al (1918), Manganese and chromium in California: California Mining Bureau. Bulletin 76: 31; Murdoch, Joseph & Robert W. Webb (1966), Minerals of California, Centennial Volume (1866-1966): California Division Mines & Geology Bulletin 189: 297.
Pyrite
Formula: FeS2
Pyrolusite
Formula: Mn4+O2
Description: Good specimens.
Reference: Murdoch, Joseph & Robert W. Webb (1966), Minerals of California, Centennial Volume (1866-1966): California Division Mines & Geology Bulletin 189: 303.
Quartz
Formula: SiO2
Localities: Reported from at least 51 localities in this region.
'Serpentine Subgroup'
Formula: D3[Si2O5](OH)4 D = Mg, Fe, Ni, Mn, Al, Zn
Talc
Formula: Mg3Si4O10(OH)2
'Uraconite' ?
Description: Occurs as yellow ochres on pitchblende in contact with gold.
Reference: Rickard, Thomas Arthur (1895), Certain dissimilar occurrences of gold-bearing quartz (with discussion by Philip Argall): Colorado Sci. Soc. Proc.: 4: 329; Walker, G.W., et al (1956), Radioactive deposits in California: California Division Mines Special Report 49: 10, 28-29; Murdoch, Joseph & Robert W. Webb (1966), Minerals of California, Centennial Volume (1866-1966): California Division Mines & Geology Bulletin 189: 377.
Uraninite
Formula: UO2

List of minerals arranged by Strunz 10th Edition classification

Group 1 - Elements
Gold1.AA.05Au
Group 2 - Sulphides and Sulfosalts
Chalcopyrite2.CB.10aCuFeS2
Hessite2.BA.60Ag2Te
Petzite2.BA.75Ag3AuTe2
Pyrite2.EB.05aFeS2
Group 4 - Oxides and Hydroxides
Pyrolusite4.DB.05Mn4+O2
Quartz4.DA.05SiO2
Uraninite4.DL.05UO2
Group 5 - Nitrates and Carbonates
Ankerite5.AB.10Ca(Fe2+,Mg)(CO3)2
Calcite5.AB.05CaCO3
Dolomite5.AB.10CaMg(CO3)2
Group 9 - Silicates
Antigorite9.ED.15Mg3(Si2O5)(OH)4
Muscovite9.EC.15KAl2(AlSi3O10)(OH)2
var: Phengite9.EC.15KAl1.5(Mg,Fe)0.5(Al0.5Si3.5O10)(OH)2
Talc9.EC.05Mg3Si4O10(OH)2
Unclassified Minerals, Rocks, etc.
'Allanite Group'-{A12+REE3+}{M3+2M32+}(Si2O7)(SiO4)O(OH)
'Chlorite Group'-
'Hornblende'-
'Mariposite'-K(Al,Cr)2(Al,Si)4O10(OH)2
'Psilomelane'-Mn, O
'Serpentine Subgroup'-D3[Si2O5](OH)4 D = Mg, Fe, Ni, Mn, Al, Zn
'Uraconite' ?-

List of minerals arranged by Dana 8th Edition classification

Group 1 - NATIVE ELEMENTS AND ALLOYS
Metals, other than the Platinum Group
Gold1.1.1.1Au
Group 2 - SULFIDES
AmBnXp, with (m+n):p = 2:1
Hessite2.4.2.1Ag2Te
Petzite2.4.3.3Ag3AuTe2
AmBnXp, with (m+n):p = 1:1
Chalcopyrite2.9.1.1CuFeS2
AmBnXp, with (m+n):p = 1:2
Pyrite2.12.1.1FeS2
Group 4 - SIMPLE OXIDES
AX2
Pyrolusite4.4.1.4Mn4+O2
Group 5 - OXIDES CONTAINING URANIUM OR THORIUM
AXO2·xH2O
Uraninite5.1.1.1UO2
Group 14 - ANHYDROUS NORMAL CARBONATES
A(XO3)
Calcite14.1.1.1CaCO3
AB(XO3)2
Ankerite14.2.1.2Ca(Fe2+,Mg)(CO3)2
Dolomite14.2.1.1CaMg(CO3)2
Group 71 - PHYLLOSILICATES Sheets of Six-Membered Rings
Sheets of 6-membered rings with 1:1 layers
Antigorite71.1.2a.1Mg3(Si2O5)(OH)4
Sheets of 6-membered rings with 2:1 layers
Muscovite71.2.2a.1KAl2(AlSi3O10)(OH)2
Talc71.2.1.3Mg3Si4O10(OH)2
Group 75 - TECTOSILICATES Si Tetrahedral Frameworks
Si Tetrahedral Frameworks - SiO2 with [4] coordinated Si
Quartz75.1.3.1SiO2
Unclassified Minerals, Mixtures, etc.
'Allanite Group'-{A12+REE3+}{M3+2M32+}(Si2O7)(SiO4)O(OH)
'Chlorite Group'-
'Hornblende'-
'Mariposite'-K(Al,Cr)2(Al,Si)4O10(OH)2
Muscovite
var: Phengite
-KAl1.5(Mg,Fe)0.5(Al0.5Si3.5O10)(OH)2
'Psilomelane'-Mn, O
'Serpentine Subgroup'-D3[Si2O5](OH)4 D = Mg, Fe, Ni, Mn, Al, Zn
'Uraconite' ?-

List of minerals for each chemical element

HHydrogen
H Serpentine SubgroupD3[Si2O5](OH)4 D = Mg, Fe, Ni, Mn, Al, Zn
H Allanite Group{A12+REE3+}{M23+M32+}(Si2O7)(SiO4)O(OH)
H AntigoriteMg3(Si2O5)(OH)4
H MaripositeK(Al,Cr)2(Al,Si)4O10(OH)2
H TalcMg3Si4O10(OH)2
H MuscoviteKAl2(AlSi3O10)(OH)2
H Muscovite (var: Phengite)KAl1.5(Mg,Fe)0.5(Al0.5Si3.5O10)(OH)2
CCarbon
C DolomiteCaMg(CO3)2
C AnkeriteCa(Fe2+,Mg)(CO3)2
C CalciteCaCO3
OOxygen
O QuartzSiO2
O DolomiteCaMg(CO3)2
O Serpentine SubgroupD3[Si2O5](OH)4 D = Mg, Fe, Ni, Mn, Al, Zn
O AnkeriteCa(Fe2+,Mg)(CO3)2
O CalciteCaCO3
O UraniniteUO2
O Allanite Group{A12+REE3+}{M23+M32+}(Si2O7)(SiO4)O(OH)
O AntigoriteMg3(Si2O5)(OH)4
O MaripositeK(Al,Cr)2(Al,Si)4O10(OH)2
O PyrolusiteMn4+O2
O PsilomelaneMn, O
O TalcMg3Si4O10(OH)2
O MuscoviteKAl2(AlSi3O10)(OH)2
O Muscovite (var: Phengite)KAl1.5(Mg,Fe)0.5(Al0.5Si3.5O10)(OH)2
MgMagnesium
Mg DolomiteCaMg(CO3)2
Mg Serpentine SubgroupD3[Si2O5](OH)4 D = Mg, Fe, Ni, Mn, Al, Zn
Mg AnkeriteCa(Fe2+,Mg)(CO3)2
Mg AntigoriteMg3(Si2O5)(OH)4
Mg TalcMg3Si4O10(OH)2
Mg Muscovite (var: Phengite)KAl1.5(Mg,Fe)0.5(Al0.5Si3.5O10)(OH)2
AlAluminium
Al Serpentine SubgroupD3[Si2O5](OH)4 D = Mg, Fe, Ni, Mn, Al, Zn
Al MaripositeK(Al,Cr)2(Al,Si)4O10(OH)2
Al MuscoviteKAl2(AlSi3O10)(OH)2
Al Muscovite (var: Phengite)KAl1.5(Mg,Fe)0.5(Al0.5Si3.5O10)(OH)2
SiSilicon
Si QuartzSiO2
Si Serpentine SubgroupD3[Si2O5](OH)4 D = Mg, Fe, Ni, Mn, Al, Zn
Si Allanite Group{A12+REE3+}{M23+M32+}(Si2O7)(SiO4)O(OH)
Si AntigoriteMg3(Si2O5)(OH)4
Si MaripositeK(Al,Cr)2(Al,Si)4O10(OH)2
Si TalcMg3Si4O10(OH)2
Si MuscoviteKAl2(AlSi3O10)(OH)2
Si Muscovite (var: Phengite)KAl1.5(Mg,Fe)0.5(Al0.5Si3.5O10)(OH)2
SSulfur
S ChalcopyriteCuFeS2
S PyriteFeS2
KPotassium
K MaripositeK(Al,Cr)2(Al,Si)4O10(OH)2
K MuscoviteKAl2(AlSi3O10)(OH)2
K Muscovite (var: Phengite)KAl1.5(Mg,Fe)0.5(Al0.5Si3.5O10)(OH)2
CaCalcium
Ca DolomiteCaMg(CO3)2
Ca AnkeriteCa(Fe2+,Mg)(CO3)2
Ca CalciteCaCO3
CrChromium
Cr MaripositeK(Al,Cr)2(Al,Si)4O10(OH)2
MnManganese
Mn Serpentine SubgroupD3[Si2O5](OH)4 D = Mg, Fe, Ni, Mn, Al, Zn
Mn PyrolusiteMn4+O2
Mn PsilomelaneMn, O
FeIron
Fe Serpentine SubgroupD3[Si2O5](OH)4 D = Mg, Fe, Ni, Mn, Al, Zn
Fe AnkeriteCa(Fe2+,Mg)(CO3)2
Fe ChalcopyriteCuFeS2
Fe PyriteFeS2
Fe Muscovite (var: Phengite)KAl1.5(Mg,Fe)0.5(Al0.5Si3.5O10)(OH)2
NiNickel
Ni Serpentine SubgroupD3[Si2O5](OH)4 D = Mg, Fe, Ni, Mn, Al, Zn
CuCopper
Cu ChalcopyriteCuFeS2
ZnZinc
Zn Serpentine SubgroupD3[Si2O5](OH)4 D = Mg, Fe, Ni, Mn, Al, Zn
AgSilver
Ag HessiteAg2Te
Ag PetziteAg3AuTe2
TeTellurium
Te HessiteAg2Te
Te PetziteAg3AuTe2
AuGold
Au GoldAu
Au PetziteAg3AuTe2
UUranium
U UraniniteUO2

References

Sort by

Year (asc) Year (desc) Author (A-Z) Author (Z-A)
Storms, William H. (1894), Ancient Channel System of Calaveras County: California Mining Bureau (Report 12): 482-492.
Turner, Henry Ward (1894), Geological atlas, Jackson (California) folio (Folio No. 11): 1-6.
Ransome, Frederick Leslie (1900), Description of the Mother Lode district, California: USGS Geological Atlas, Mother Lode (No. 63), 11 pp.
Lindgren, Waldemar (1911), The Tertiary gravels of the Sierra Nevada of California: USGS Professional Paper 73, 226 pp.: 209-210.
Knopf, Adolf (1929), The Mother Lode system of California: USGS Professional Paper 157, 88 pp.; […(abstract): Engineering & Mining Journal: 128: 24 (1929); […Geol. Zentralbl., Band 41: 364-367 (1930)]: 70-71.
Franke, Herbert A. & C.A. Logan (1936), Mines and mineral resources of Calaveras County: California Division Mines (Report 32): 32: 235-364.
Clark, Wm. B. & P.A. Lydon (1962), Mines and mineral resources of Calaveras County, California: California Division of Mines & Geology County Report 2; [… Geological Society of America Proceedings, 1933: 312-313, 1934]: 32-93.
Clark, Wm. B. (1970a) Gold districts of California: California Division Mines & Geology Bulletin 193: 114.

Localities in this Region


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